Lockout switch



April 21, 1931. H wHlTE 1,801,829

LQCKOUT SWITCH Filed Jan. 2, 1926 WLTNESSES: INVENTOR- 5 67. WW Hare/a E Wh/ fe.

7M AT-TORNEY 7 '15 In th My invention relates Patented Apr. 21, 1931 Locxour swn'crr Application filed January 2,1928. Serial No. 78,804.

to electromagnetic switches and it has particular relation to switches of the lockout type.

An object of my invention is to simplify the construction and improve the operation of lockout switches.

, Another object of my invention is to provide a switch of such character that its operativeness shall not be materially aflfected by vibration and shocks produced by external sources. a

Other objects of my invention will become apparent in the following specification and claims appended thereto.

e use of switches of the lookout type, dlfiiculty is sometimes experienced, on account of premature closure of the switch, asthe result of vibrations of such magnitude that the flux induced by the current fails to properly lock out the switch armature. An-

other reason for such failure is inherent in the construction of the majority of switches in that the lockout point, or point at which the switch armature is released,- is not clearly defined.

In accordance with my invention, I. utilize the saturation phenomena in magnetic iron to improve the stability and general per- 1 formance of the magnetic switch. I provide A a magnetic shunt of material, such as soft iron, of relatively high permeability. This shunt is located in the air gap between the armature of the switch and its lockout magnet. At a predetermined value of current traversing the coil of the lookout magnet, the magnetic shunt becomes saturated and the additional flux, or leakage flux, traverses the magnet armature which, inits initial position, is in engagement with the shunt mem- 40 b er. I have discovered that, for all values of current above this saturation point, the switch armature is positively sealed and restrained from closing, whereas, if current in the coil'decreases to a point where the shunt member is no longer saturated, the armature is no longer restrained and the switch is permitted to close under. the operation of the closing force.

My invention will be best understood by reference to t which Figure 1 is a view in side elevation of a two-pole, or double-coil, switch of the lockout type;

Fi 2 is a diagrammatic view of a modified orm of the switch illustrated in Fig. 1, inccprporated in a system of motor control; an

Figs. 3 and 4. are views in side elevation and in plan, respectively, of a multiple-finger accelerating relay incorporating the peculiar features of my invention.

With reference to Fig. 1, it will be observed that the switch, in its main structure, corresponds to common practice, such as the switch illustrated in the Deutsch Patent N 0. 1,339,922, issued May 11, 1920 and assigned to the Westinghouse Electric & Manufacturing Company. The lockout magnet of my switch, however, differs from the Deutsch switch as will be described.

A pivotally mounted armature 1 is normally biased by the action of gravity to the illustrated lockout position, and is designed to be restrained in that position by means of a lockout magnet comprising a core memer or pole-piece 2 and an operating coil 3. closing coil 4 is provided to actuate the armature 1 against the bias of the lockout coil 3. Movable and stationary contact members 5 and 6, respectively, of any suitable character are employed.

A magnetic shunt member 7, in the form 01 a U-shape strip of relatively thin soft iron, is so constructed as to carry flux traversing the core member 2. The shunt member is preferably in contact with the inner end of the pole piece 2 and extends into the air gap between the other end of pole piece 2 and the armature member 1. As illustrated, the lower end of the armature 1 rests against a portion of the shunt 7. The air gap of the switch is adjusted by means of a compression member comprising a still spring 8 that bears against shunt 7 and is mounted on a stud 9 traversing a hole 11 in the end of the shunt. The position of the shunt 7, and the initial position of the armature 1, is adjusted by 100 e accompanying drawing, in

to be connected across all monly employed for starting motors. the lockout coil 3 is energized to a low degree, a small amount ting,jat which little or no the shunt member the outer end of stud 9.

I have thus illustrated simple means for adjusting the position of the shunt member 7 but any suitable adjustment may be provided whereby the relative positions of the armature and pole-pieces may be adjusted to accurately determine the setting of the lookout switch. The setting of the switch may also be changed, of course, by varying the strength of the lockout-magnet, as by providing lock-z out coils of different numbers of turns. I preferably employ a shunt-type coil adapted or any portion of a resistor, such as the accelerating resistor com- When of' magnetic flux traverses the pole-piece2 and the shunt 7 v V By increasing the excitation of the coil 3., a point is reached at which the shunt 7 becomes saturated and, is unable to carry all the flux traversing the pole-piece 2, so that the excess flux then traverses the armature. member 1 and, on'account of the physical contact between the members 1 and 7, the armature is securely sealed in the illustrated position. It will be evident that the'pull of the closing coil 4 will be'insulficient to operate the switch until its armature is released by reason 0 magnet 3 to a predetermined value, or setflux from the polepiece 2 enterst-he armature 1 and the flux traverses a local circuit comprising the polepiece'and the shunt member ,7 7 5 To illustrate the efiectiveness of my lockout structure, I found that with one hundred percent increase in' current traversing the closing coil 4, aseven percent increase in currentin the lockoutc oil' 3 was suflicientto keep the switch from operating. 1 also discovered that the point at whichthe switch releases is very accurately defined in contrast to the uncertain operation of many switches heretofore employed. V Fig. 2 illustrates a lookout switch utilizing the same principle of operation as that set forth in connection with Fig. 1, the @switch structure, however, being somewhat different.

In this instance, the pole-pieces comprise core members 13 and a U-shapemember 14 across theopen end of which is connected a shunt The switch armature 21 normally rests upon 17 and is disengaged therefrom only through the action of the closing coil4, which acts in opposition to the lockout coil 3, in a manner previously described; The lockout coil 3 is connected-across an accelerating resistor 22, such as is commonly employed for controlling the operation of a motor, for example, the illustrated directcurrent motor comprising an armature 23 and a series field-magnet winding 24. 7

means of lock nuts '12 that are mounted on f members28, 29 and 30, respectively. areduction in the excitation of the lookout.

' the pole-piece sufficient, however,

member 17 comprising a strip of soft iron.

switches of afamiliar type,

In the form of my invention herein illustrated, the initial or peak accelerating cur rent traversing the lockout coil 3 saturates the magnetic shunt 17, and the leakage flux, therefore, traverses the armature member 21. As the motor armature 23 accelerates and the starting current is reduced to a minimum, the flux traversing the pole-pieces 13 and 14 becomes insuflicient to saturate the shunt 17, whereupon armature 21 isreleased and: the switch is closed, by the action of the operating coil 4, to short-circuit the starting resistor '22.

, In Figs. 3 and 4, I have illustrated my invention as applied to a multiple-finger accelerating relay of the type illustratedlin De Camp Patent tember 27, 1921. This relay, as commonly constructed, is open indicated, in connection with the operation of lockoutswitches, when subjected to vibration or shocks, if the controllers are mounted on shipboard or on any vehicle, for example.

It is believed 'tobe unnecessasry to describe the details and operation of the DeCamp relay, since it is clearly described in the above-identified patent. It will be sutficient to note thatI have provided a magnetic shunt 27 for each of the successively movable switch fore, when the relay coilis over-exclted by peak currents, the magneticjfluxvtraversing 10 in part traverses the shunt member 27 and in part-the corresponding finger,.such as 30, for example and the finger is restrained in its illustrated positionuntil the excitation .of the relay. coil .isreduced to aminimum,'when all the flux traversing the pole-piece 10 can be carried by the shunt member 27 at which time the finger-30 is actuated by the spring 31; 1 v

Certain of the :minor structural details of the De Camp relay have been modified and simplified, as incorporated in my invention, although thevprincipl of operation and the structure in general remains the same. The simple improvement to .greatly improvev the operation of this otherwise elficient relay,

thereby adapting it toamanyfapplications where severe vibration will disturb the setting of relays otherwise constructed in .accordancewith familiar practice.

My invention has been describ. d and illustrated in preferred forms in connection with and it will be obvious that various other modifications may be made bythoseskilled departing from. the spirit of my invention. I desire, therefore, that my invention shall be limited only in accordance with the scope of-the appended claims. -I claim as my invention: V

1. A lockout switch comprising a movable armature member, a stationary pole-piece, a

No. 1,392,249, issued fSep.-'

Therewhich 'I have added, is.

in the art without I movable armature, a

shunt member for deflecting flux from said armature member,

a portion of said shunt member being disposed between said polepiece and said armature member, and means or adjusting the position of a portion of said shunt member and of said armature, simultaneously, with respect to said stationary pole-piece.

In a lookout switch, in combination, a movable armature, a magnet for actuating oppose the operation of the armature by the actuating magnet, a magnetic shunt looped around the holding magnet and extending between the magnet and armature and means magnetic shunt relative to p g magnet and armature thereby to control the operation of the armature.

3. In a lockout switch, in combination, a

the armature, a holding magnet disposed 1to t e actuating magnet, a magnetic shunt lo oped around the holding magnet, one arm of the magnetic shunt extending between the holding magnet and armature and means for adjusting said arm of the magnetic shunt relative to the holding magnet to vary the air gap between the shunt and holding magnet to control the operation of the armature.

4. In a lockout switch, in combination, a movable armature, a magnet for actuating the armature, a holding magnet disposed to oppose the operation of the armature, a mag netic shunt simulating a clevis looped about the holding magnet, one arm of the shunt extending between the holding magnet and armature and means for adjusting the arms of a shunt relative to one another to vary the air gap between the armature and holding magnet to control the operation of the armature. v

In testimony whereof, I have hereunto subscribed my name this 29th day of December,

HAROLD E. WHITE. 

